With the development of the so-called third-generation portable telephone systems in recent years, it is becoming possible to install base stations for femtocells with a coverage range having a radius on the order of several tens of meters in offices and residences, to access nodes such as stationary terminals of home NW (Network) or office NW from portable mobile terminals, and to operate these nodes.
An example of a communication system that incorporates this type of femtocell base station is described in 3GPP TR 25.820 V8.0.0 “3G Home Node B Study Item Technical Report (Release 8)” (hereinbelow referred to as Document 1).
FIG. 1 is a block diagram showing an example of the configuration of a communication system that incorporates the femtocell base station described in Document 1.
As shown in FIG. 1, this communication system is made up from: mobile terminal ISP (Internet Service Provider) network 301, Home GW (Gateway) ISP network 302, access network 303, and home NW 304.
In addition, mobile terminal ISP network 301 includes HSS (Home Subscriber Server) 311, PDN (Packet Data Network)-GW 312, MME (Mobility Management Entity) 313, and Serving GW 314; Home GW ISP network 302 includes router 321; access network 303 includes BAS (broadband Access Server) 331; and the home NW includes mobile terminal 341, femtocell base station 342, Home GW 343, and stationary terminal 344.
The operations of a communication system having this type of configuration are next described.
FIG. 2 is a flow chart for describing an example of the operations of the communication system shown in FIG. 1.
As shown in FIG. 2, mobile terminal 341 first transmits to femtocell base station 342 an attach request as an access request for accessing a network by way of femtocell base station 342 (Step 700).
Femtocell base station 342, having received the attach request, transmits an attach trigger to MME 313 by way of Home GW 343, BAS 331, and router 321 (Step 701).
MME 313 receives the attach trigger and, upon detecting the attach request of mobile terminal 341, implements the access authentication of mobile terminal 341 (Step 702).
Upon success of the access authentication of mobile terminal 341, MME 313 transmits a data path generation request to Serving GW 314 (Step 703).
Upon receiving the data path generation request, Serving GW 314 exchanges signaling for generating a data path with PDN-GW 312 and generates a data path between Serving GW 314 and PDN-GW 312 (Step 704). Serving GW 314 then transmits a data path generation response to MME 313 to report the completion of data path generation (Step 705).
Upon receiving the data path generation response, MME 313 transmits a data path generation request to femtocell base station 342 to generate a data path as far as mobile terminal 341 (Step 706).
Upon receiving the data path generation request, femtocell base station 342 generates a data path with mobile terminal 341 (Step 707) and transmits a data path generation response to MME 313 (Step 708).
A data path is thus generated between mobile terminal 341 and PDN-GW 312, whereby mobile terminal 341 is able to access the network from PDN-GW 312 via mobile terminal ISP network 301. Mobile terminal 341 subsequently is able to access and manipulate stationary terminal 344 in home NW 304 via the network.